Power converters are commonly used to convert alternating current (AC) power from a generator to direct current (DC) power, and from DC power to AC power for use by a motor. Power conversion requires switching of large currents by power semiconductor devices, such as insulated gate bipolar transistors (IGBTs). An electric drive traction application typically includes both AC/DC conversion to receive power from a generator and DC/AC conversion to power a motor. The generator is typically driven by an engine.
The IGBT power modules are the heart of the inverter for converting DC power to AC power. The IGBT modules are densely packaged with the rest of the inverter components. The IGBT modules dictate the shape and position of the AC and DC bus bars, the configuration of the gate driver boards, and the configuration of one or more heat sinks provided to dissipate heat generated as electric current flows through the IGBT devices included in each IGBT power module. Switching to a different power module typically requires redesigning the adjoining components.
Most electric drivetrains for machines use induction motor/generator technology or permanent magnet (PM) motor/generator technology. In either case, the power inverter architecture is the same and uses power modules optimized for this application. Such power modules have insulated gate bipolar transistors (IGBTs) and diodes packaged in a configuration that supports induction/PM applications. The power modules for induction/PM applications are configured to receive or provide power in multiple phase configurations, such as a three phase (X, Y, Z) configuration.
However, many drivetrain applications are moving to switched reluctance (SR) motor technology, which offers a simpler rotor design at the expense of more complex motor controls. SR technology also uses IGBTs and diodes, but requires a power module with a different configuration than induction/PM technology. The power modules for SR applications are not limited to a three phase output. The number of outputs is determined by the number of stator poles and rotor poles and therefore may have more than three outputs.
Different power inverter applications may also have different requirements for locations of external connections and configurations of a protective enclosure in which the IGBT modules are contained. In applications requiring power inverters for multiple electrical machines, such as multiple AC electric motors, additional pairs of IGBT devices or other power semiconductors for each additional electrical machine are often added in a linear arrangement to a long heat sink, resulting in a power inverter enclosure that may be exceedingly long in one dimension. As the number of pairs of power modules increases, the power modules are connected in parallel, and the amount of current flowing through the power modules increases for high power applications such as portable power generating plants, and large mining and other earth moving machines, it becomes important to balance the amount of electrical power carried by each module. A well balanced power inverter assembly will have better performance and durability than an inverter assembly where some of the power modules carry different amounts of electrical power than others.
European Patent Application No. EP 1 445 853 to Still et al., published August 11, 200, entitled “Converter Module” (“the '853 publication”), discloses a converter module including a heat sink and a semiconductor phase mounted on the heat sink. A pair of semiconductor modules include an AC bus bar connected to the emitter of one semiconductor module and the collector of the other semiconductor module, and a pair of DC bus bars connected respectively to the remaining collector and emitter terminals of the pair of semiconductor modules.
The disclosed system and methods are directed to overcoming one or more problems set forth above.